*URGENT* Got 403 errors when trying to move a user from 1 usergroup to another!!

[محروم.كوم]

I have a Super Moderator that is causing A LOT of issues, and I need to move him to another usergroup. Once I select the usergroup to move him to, it gives me this error:

Quote:
You don't have permission to access /admincp/user.php on this server.


Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request

It has never done this before and it is only doing it for a few different user names.

I really need to fix this, and REALLY will appreciate all help that comes along!

(Also, I tried changing the htaccess mod_security, but that didn't work)

All help is greatly appreciated! __DEFINE_LIKE_SHARE__